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Brand new first motion shaft for 4 synchro pre-A+ gearboxes using the early 14mm noses. This "close ratio" gear was used in all Cooper "S" and 1275GT gearboxes to 1979, and has 18 teeth and has no grooves cut into the teeth. Later pre-A+ "S" gearboxes used a similar gear but with a wider 18mm A+ mainshaft. The 1st motion shaft serves as both fourth gear as well as the transmission input shaft, and recieves alot of abuse. If a bearing in the gearbox fails then this shaft can get destroyed quickly. 


Often times a crunch while engaging a gear is a result of a failed synchro ring, however if left ignored the gear and selector will start to get damaged. If you see any chipping or broken selector teeth, pitting on the synchro surface, or any wear on the actual helical teeth, it is time to replace the gear.

4th Gear / Input Shaft - Pre-A+18 Tooth (14mm Mainshaft)

SKU: 22G1371
Sorry, Out of Stock

Pre-A+ "S" (Close Ratio) 4 sync gearboxes w/ 14mm mainshaft nose.

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